1. Field of the Invention
The present invention relates to a camera which is equipped with a device which detects the visual line of the photographer and a method of photography using this device.
2. Related Background Art
A camera has been previously proposed, for example in U.S. Pat. Nos. 3,836,670, 4,950,069, and 5,036,347, which is equipped with such a type of device for detecting the visual line of a person using the camera. This type of visual line detection device, for example, is constructed so as to shine infra-red radiation onto the eyeball of a photographer looking into the viewfinder of the camera from an infra-red illumination device provided within the camera, and so as to detect which part of the region visible within the viewfinder is currently being focused upon by the photographer based upon radiation reflected from the eyeball of the photographer. The device is termed a visual line detection device which in this manner, by sensing radiation reflected from the eyeball of the photographer, detects which region of the field visible within the viewfinder is being gazed at and focused upon by the photographer, i.e. at which region the photographer is directing his or her attention.
If the region of the photographic field which is being focused upon (fixated upon) by the photographer is determined by such a visual line detection device, afterwards focusing of the camera on an object located in this region of the photographic field can be performed by moving a lens of the camera by using a typical per se known type of auto-focusing device, and also the most suitable exposure can be determined and set by the use of a per se known type of automatic exposure determination and setting device. Thus even an inexperienced photographer is enable to perform photography while minimizing mistakes.
From the following viewpoints, it is necessary to correct the visual line as determined by the use of such a type of visual line detection device.
1) The position at which the photographer is actually directing his or her attention (fixating), and the point of attention of the photographer as determined by such an above type of visual line detection device, do not necessarily always agree, and moreover the difference between these two positions varies between different photographers, according to the personal characteristics of their eyeballs, etc.
2) The curvature of the eyeball varies according to the individual photographer.
For these reasons, with the cameras disclosed in the above identified U.S. Patents, before normal photographic operation a different operation is previously performed by hand, and information (hereinafter termed calibration information) which is necessary for the above described correction is input into the camera and is stored therein.
A camera equipped with a visual line detection device according to the prior art as described above in which such a correction process is performed is subject to the following deficiency.
If a second person (Mr. B) wishes to use a camera into which calibration information suitable for a first person (Mr. A) has already being input and stored, then, before performing photography, Mr. B must perform an operation for inputting calibration information appropriate to his own eyeball which differs from normal photographic operation; and this makes the camera difficult to use. Further, if erroneously this new calibration information is not obtained, and instead photography is performed by Mr. B while the old calibration information appropriate to Mr. A is still stored in the camera, then the correction of the visual line of the photographer will be performed using the old incorrect calibration information, and it is likely that an incorrect visual line will be determined.
A further problem can arise in the case of a photographer who does not have a strongly dominant eye. Most people always use a dominant or favorite eye for looking through a restricted aperture such as a telescope, a microscope, or a camera viewfinder; but a minority of people freely use either eye for such purposes. Since the left and right eyeballs even of the same person typically may differ substantially in their curvature characteristics (astigmatism etc.), this can present a problem with regard to inconsistency of calibration information, similar to the problem described above with regard to the camera being used by two different camera users.